1. Field of Invention
The present invention relates to a method for manufacturing cement fiber sheets, and more specifically to a technique for manufacturing cement fiber sheets, for example, used for exterior construction material (siding board, roofing tiles, etc.), exterior products (fences, gates, etc.), and interior construction material (floors, walls, ceiling, etc.).
2. Description of Related Art
Conventionally, in manufacturing these types of cement fiber sheets, there is known a construction method for manufacturing cement fiber sheets in which slurry including fiber and cement materials is discharged from a discharging port for controlling the thickness supplied onto permeable sheets, suctioned and dewatered.
However, accumulated foreign matter constantly enters the slurry from, for example, compounding equipment, mixing equipment, piping, pumps, etc., and falling matter also enters. If the foreign matter enters, the foreign matter may directly affect the product appearance and in particular, depending on the size of foreign matter, holes, cracking, or tears may result. In addition, when slurry containing foreign matter passes the discharging port for controlling thickness, fine foreign matter is caught by the discharging port, which results in degradation of product surface quality, and as result, the product does not meet the product thickness standard.
The present invention has been achieved in view of the problems of the above-mentioned conventional examples, and it is an object of the present invention to provide a method for manufacturing cement fiber sheets which can eliminate foreign matter in the slurry, thereby the thickness can be positively controlled and the product surface quality is ensured.
In the present invention, to solve the problems mentioned above, a method for manufacturing cement fiber sheets is provided in which slurry primarily including fibers and cement as material components is supplied onto a permeable sheet, then suctioned and dewatered. The method also includes a foreign matter removing process for removing foreign matter contained in the slurry material before supplying the slurry to the permeable sheet, a thickness control process for controlling slurry to a specified thickness after the foreign matter removing process, and a leveling process for smoothing the slurry surface after the thickness control process. These processes eliminate detrimental effects of foreign matter on the product appearance and at the same time make it possible to prevent holes, cracking, or breakage in products beforehand by providing a foreign matter removing process, and consequently, the product surface quality is ensured and thickness control is positively implemented.
In addition, the slurry concentration is desirably between 35 and 65%, and in such event, the fluidity of slurry is proper and effects of ensuring the product surface quality, as well as effects of positively implementing thickness control and leveling can be expected, and at the same time, the problem of ease of spilling of slurry can be simultaneously solved.
In implementing the leveling process of the present invention, a leveling device equipped with a smooth-forming pressure plate is desirably used for pressing and smoothing the slurry surface and at the same time, an endless sheet is desirably positioned rotatably between the slurry surface and smooth-forming pressure plate. Thus, it is possible to prevent cracking caused by chafing between the slurry surface and the leveler and at the same time the problem of product surface quality being degraded by the leveler itself can also be eliminated.
In implementing the thickness control process, it is desirable to use a thickness controller provided with a discharging port for discharging slurry to a specified thickness and to use a leveler for imparting vibrating action to the discharging part, and in such event, when slurry is discharged from the discharging port, it is possible to simultaneously control slurry thickness by the discharging port and to smooth the slurry surface by the vibrating action.
According to an aspect of the present invention a method is provided for manufacturing cement fiber sheets in which slurry primarily including fibers and cement as material components is supplied onto a permeable sheet, and then suctioned and dewatered. The method includes removing foreign matter contained in the slurry material before supplying the slurry to the permeable sheets, controlling a thickness of the slurry supplied to the permeable sheet and smoothing the slurry surface after the thickness control process.
According to a further aspect of the present invention, in the method a slurry concentration of between 35 and 65% is used.
Further according to an aspect of the present invention, the leveling operation is carried out by a leveler equipped with a smooth-forming pressure plate for pressing the slurry surface for smoothing, and at the same time an endless sheet is rotatably intervened between the slurry surface and the smooth-forming pressure plate.
Furthermore, according to another aspect of the present invention, in the method, when the thickness control operation is carried out, a thickness controller equipped with a discharge port for discharging slurry to provide a specified thickness and a leveler for providing vibrating action to the discharging port are used.